1. Field of the Invention
The invention relates to a warning device for a vehicle, which issues a warning based on the operating state of a vehicle.
2. Description of the Related Art
There is a conventional vehicle having steering assist control functions such as a lane keeping assist function of assisting a driver in executing a steering operation and a lane changing assist function of assisting a driver in changing the lane in order to facilitate travelling of the vehicle along a travelling path. For the purpose of informing a driver of an undesirable steering state during execution of steering assist control, a warning device for a vehicle, which vibrates a steering wheel to issue a warning to the driver, has been being developed, as described in, for example, Japanese Patent No. 4292562 and Japanese Patent Application Publication No. 11-34774.
However, the vibration that is given from the warning device for a vehicle of this type to the steering wheel as a warning (hereinafter, referred to as “warning vibration”) may be lost in road noise that is transmitted from a road surface to a steering member through tires. This makes it difficult to transmit the warning vibration to the driver. Therefore, it is necessary to prevent the warning vibration from being lost in the road noise.